1. Field of the Invention
The present invention relates to an electrolytic capacitor and a method of manufacturing the same.
2. Description of the Related Art
An electrolytic capacitor having an anode foil and a cathode foil wound together around an axis and an electrode lead attached to each of them has widely been used. For example, Japanese Patent Laying-Open No. 2004-179621 discloses an electrolytic capacitor having two cathode lead terminals and two anode lead terminals, that is, four lead terminals in total. A plurality of cathode lead terminals and anode lead terminals are provided, in order to lower equivalent series inductance (ESL) and equivalent series resistance (ESR).
Unbalanced arrangement of the four lead terminals above may cause a problem in a process for manufacturing a capacitor or a process for mounting a capacitor. This problem is represented, for example, by concentration of stress on some terminals, lowering in hermeticity in sealing, or tilting of a capacitor with respect to a mount surface. In order to avoid this problem, the four lead terminals above are desirably arranged as symmetric as possible with respect to an axis of winding above. Specifically, in a two-dimensional layout, the four lead terminals are desirably arranged in a manner substantially corresponding to four respective vertices of a square having the axis of winding above in the center. In order to achieve such arrangement, a distance between each of the four lead terminals and the axis should substantially be equal.
As winding proceeds, however, the distance between each foil and the axis increases, and hence difference is produced in the distance between each of the two lead terminals arranged at different positions in each foil and the axis. Therefore, it has been difficult to arrange four lead terminals in a manner substantially corresponding to four respective vertices of a square having the axis in the center.